It is known that chemistry is a BIG part of our everyday lives. You can find chemistry in daily life in foods you eat, air you breathe, soap, your emotions and literally every object you can see or touch. For example, Chemistry explains how food changes as you cook it, how it rots, how to preserve food, how your body uses the food you eat, and how ingredients interact to make food.
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Answer:- 448 mL of hydrogen gas are formed.
Solution:- It asks to calculate the volume of hydrogen gas formed in milliliters at STP when 0.020 moles of magnesium reacts with excess HCl acid. The balanced equation is:

There is 1:1 mol ratio between Mg and hydrogen gas. So, the moles of hydrogen gas is also equals to the moles of Mg reacted.
moles of Hydrogen gas formed = 0.020 mol
At STP, volume of 1 mol of the gas is 22.4 L. We need to calculate the volume of 0.02 moles of hydrogen gas.

= 0.448 L
They want answer in mL. So, let's convert L to mL using the conversion formula, 1L = 1000mL

= 448 mL
So, 0.020 moles of magnesium would produce 448 mL of hydrogen gas at STP on reacting with excess of HCl acid.
Answer:
The correct answer is "obligatory water reabsorption in the proximal convoluted tubule".
Explanation:
The mechanism for producing concentrated urine cannot include the obligatory reabsorption of water in the proximal convoluted tubule since this process is part of the nephron, the system that filters the blood. Glucose and amino acids are reabsorbed almost entirely, as are approximately 70% of filtered potassium and 80% of bicarbonate.
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Answer: An atom with 6 protons, 5 electrons, and 7 neutrons
Explanation: In this case, neutrons do not matter as they have a charge of 0, or no charge. A proton has a charge of +1 and an electron has a charge of -1. Since there are 6 protons, the total charge of the protons would be +6. Since there are 5 electrons the total charge of the electrons would be -5. +6 - 5 would result in a charge of +1. This means that this atom would have an overall charge of + 1. Basically, if there is one more proton than electron, then the overall charge of the atom will be +1 but if there is one more electron than proton, then the overall charge of the atom will be -1.